How do you determine "at the lands" by your method?

[Brent]

I use a FL sized case and split the neck with a dremmel.

Len,
If you're "careful", you can cut the coil spring back (cut off wheel in a dremmel works) incrementally until you get the desired plunger pressure, or simply remove it if you shoot single shot only like one of mine is. The factory spring is VERY high pressure, it will often dent the case mouth as it slips from the chamber and hits the inside of the receiver ring, and if you don't use an expander (I don't) in your die, you will have to then. The ejector itself is seperate from the firing pin assembly BTW.

 

[Budman]

Could you not do a chamber casting and get the measurement? I have to average the measurement with the stoney point tool also as I seldom get the measurement.

 

[BountyHunter]

1. Sinclair and Stoney Point seating depth tools are usable if you understand the tools nuances and take repeated measurements. Buy one of them as both are around $30.

2. Jam seating and looking for marks will give you bout .040-.050 into lands. A place to start, but impossible to accurately measure throat erosion and adjust seating to accomodate. More commonly known as SWAG.

3. Stoney point comparator set ($26.50) for accurate dial caliper is essential for any measurement of seated bullet. Buy it first!!!

4. Unless AOL is issue, then above 1 and 2 is meaningless. What matters is you seat into the lands (even as deep as .040) tune until best groups with powder variances then tune for seating depth last. Fine tune depth at that point at .002 increments. Then make measurements of seated bullets with Comparotor. Which is the only measurement you need. Ie where does the gun shoot best.

5. All the above is meaningless again unless you are sorting bullets by base to ogive (spot on bullet where it touches lands) lengths. Sierra bullets from same box have varied by .030 on where ogive starts. Unless sorted kills any standard touching point of lands.

Custom bullets will vary as little as .003 in batch of 500, but can vary by as much as .020 from one lot to the other.

6. Quality inline or Micrometer seating dies are essential if you are serious about this.

7. RW Hart sells the best tool for sorting bullets and it is called the Buhay Ogive checker ($125 for one caliber). Zero variance with dial indicator under spring pressure. However, stoney point comparator ($30) clipped to caliper blade used to measure base to ogive is accurate as long as you watch the pressure closing blades.

BH

 

[BountyHunter]

Ogive checking just came in within the last 2-3 years or so. So do it and some do not. I am not the Ballistics guru and tester that some are. Henry Childs on BR central (goes by HBC) is the leader in this.

He has done serious testing and says it really takes out lot of vertical, but more importantly "rounds" out the groups.

His big thing now is metplats. Ie uniforming them to standard length from ogive. Either the Tooley tool or the one from Kevin Cram (Montour Rifles). Cuts BC by .2% on average. Non uniformity can cause a 5% BC variance which is 6 inches vertical at 1000.

Tooley is cutting tips off and installing own plastic tips on some bullets.

Dave and Steve Shelp tested the new Clinch River 6.5 cal 140 grain "flatbase" bullet this weekend in Ohio and kicked butt. Think about 4 five and four inch groups for light guns. Seems to like a 9 twist barrel.

BH

 

[Len Backus]

BountyHunter

Please clarify. "Cuts BC by .2%", do you mean 2.0 % ?

.2 % is only taking a bullet from .750 down to .748
That's no bad.

 

[Brent]

These are obviously some of the finer points in handloading and I know I've heard plenty of people say they do it all, some for confidence, some say it all shows improvements.

I can't help but wonder what the difference would be if you took normal cafefully prepped brass, turned and such, no detail missed, then seated bullets that never went through any sorting inspection process and compared them to same load with bullets that had been through every uniforming procedure mentioned, even spun on the Verne Juenke ICC...

If there was an advantage of increased precision to doing all the work on bullets, one should see a the largest improvement by doing everything he could to one batch of loads and nothing to the other, although you would have to isolate the advantage contributed by each step if you wanted to eliminate any that might prove un-useful.

Has anyone done this sort of all or nothing comparison before? If so, what did you find and how confident are you other variables were not influencing the testing?

 

[a.JR]

Len,After making my 4th different design Meplat trimmer i have settled on the tooley design with an easier adjustment set up..This is about as simple and efficent a product you can get and dave sells em for about 40 bucks i understand ..Just before our recent state champs i tested the 187BIBs with and without the meplat trimming..Results were cutting the bullet AOL back to 1.320 long from approx 1.325to 1.328 gave a loss of 3/4s MOA (down the paper) @ 1K..I don't know(care)what the loss in bullet speed at target that equates to..I do know that if you want to shoot sub 5 inch 10 shot at 1000yds unless you are a very lucky fellow then bullet equalization is paramount..We have completed 4 1K matchs at my home range so far this year ,my Agg for the 4 is 7.290 inchs..Also an added advantage in meplat trimming is after cutting it is possible to see if the ogive forming has put any folds in the jacket..JR..Jeff Rogers

 

[Len Backus]

Jeff

You are the guy I had in mind when I posted my question. I remembered you posted over on BR about the meplat trimmer.Thanks for chiming in. Your 1/4 moa suggests about one inch more drift at 10mph. Not much.

 

[a.JR]

Len,Your right about the drift ,i will give away drift anytime for a gain in vertical dispersion(VD)..My range in tropical Northern Australia is where mirage was invented so vertical will always be a hefty problem for groups ..The toughest part of long range load develpoment will always be the VD. IMO..Lookin back at one of your posts u mention the chrono and bullet qualifing,i sorry i don't have that info as i don't use a chrono for load testing..Your question on the differences between sorted and unsorted is a tough one as i have been basic qualifing (weight, dia,base to ogive and AOL) since 1997..I recently coached a new guy in Light from a best of 3.5in group to a 1.8in at 550yds buy helping him set the gun and the loads and the basics on the bullets..The next step is to totally set upon the cases and the Sierra bullets to get it better..These particular 168 7mm Smks were as bad as i have seen in a factory projectile(7 thou in base to ogive and 30 thou in AOL in a single box)...Hope this helps..JR..Jeff Rogers

 

[shilen30]

Very wise words from BountyHunter. Buy the tools he states and follow the prescribed steps and you can't go wrong. The only other thing I'd add that I didn't see (maybe it is in there somewhere) is to make sure your sizing die is centered and adjusted correctly. I had a forster sizing die with the split lock ring and occasionally the die would be slighty crooked after tightenning the ring, thus causing runout. Me personally, I just took a ring off an RCBS die and after twisting the sizing die firmly onto the shell holder to allign it, I would tighten the lock ring. No more problems with run-out. I am a big fan of forster inline seating dies (regular bench rest dies). They are the father of the redding inline dies which came out as soon as the patent on the forster dies run out. You pay quite a bit more for the redding mic dies than you do for the forster dies. Personally, I don't use the mic dies. Also, the configuration of the seating plug in the forster (as well as for the redding) acceptsmany more low drag bullets than do RCBS (built off speer bullets) plugs and hornady plugs.

 

[Len Backus]

Speaking of ogive sorting...have any of you serious 1K guys done testing to see how much your 1K groups benefit from such sorting? Would 1/8 moa be a fair guess?

2nd ogive sorting question...can you see measureable chrono velocity differences? For example does the ES go down when using ogive sorted bullets? If so, how much.